Seal for controlling irrigation in basket catheters

ABSTRACT

An exemplary basket catheter includes an outer tubing housing an inner fluid delivery tubing having at least one fluid delivery port. A plurality of splines are each connected at a proximal end of the splines to the outer tubing and at a distal end of the splines to the inner fluid delivery tubing. The inner fluid delivery tubing is operable to be moved in a first direction to expand the splines; and in a second direction to collapse the splines. A porous membrane is provided over at least a portion of the inner fluid delivery tubing. A seal is provided at a proximal end of the porous membrane between the porous membrane and the outer tubing and between the porous membrane and the inner fluid delivery tubing, the seal configured for irrigating between the plurality of splines of the basket catheter while preventing fluid ingress into the outer tubing.

BACKGROUND OF THE INVENTION

a. Field of the Invention

The instant invention is directed toward a mechanical seal forcontrolling delivery of a fluid (e.g., an anticoagulant) for irrigationin basket catheters. In particular, the mechanical seal of the presentinvention may be used to help direct the fluid between splines of thebasket catheter, especially at the apexes, while preventing fluidingress into the body of the catheter to assist in preventing thrombusformation without inhibiting axial movement of a deployment mechanismfor the basket catheter.

b. Background Art

Normal heart rhythm is between 60 and 100 beats per minute. Tachycardiais a fast heart rate (usually over 100 beats per minute) caused bydisease or injury. Tachycardias may begin in the upper chambers of theheart (the atria) or the lower chambers of the heart (the ventricles).Some tachycardias are harmless, but other tachycardias are lifethreatening. Tachycardias can deteriorate to fibrillation, a disorder inwhich, the heart does not move enough blood to meet the needs of thebody.

Atrial fibrillation (AF) is the most common abnormal heart rhythm. It isa very fast, uncontrolled heart rhythm that occurs when the upperchambers of the heart (the atria) try to beat so fast (between 350 and600 times per minute) that they only quiver. Ventricular fibrillation(VF) occurs when the lower chambers of the heart (the ventricles)produce fast and erratic electrical impulses that fail to inducesynchronous mechanical contraction, such that oxygenated blood is notcirculated through the body. Fibrillation in the ventricles is alife-threatening arrhythmia demanding immediate treatment.

Before a tachycardia deteriorates to fibrillation, various proceduresmay be used to treat the heart tissue and reduce or altogether eliminatethe occurrence of fibrillations. It is well known that treatmentbenefits may be gained by creating lesions in the heart tissue, whichchange the electrical properties of the tissue, if the depth andlocation can be controlled. For example, cardiac ablation techniques areknown for forming lesions at specific locations in cardiac tissue tolessen or eliminate undesirable atrial fibrillations. Likewise, biologicand chemical agents may be delivered into infracted tissue in the lowerchambers of the heart (the ventricles) to promote angiogenesis for thetreatment of Ventricular Tachycardia (VT). Other procedures are alsoknown for treating these and other ailments. Use of a particularprocedure depends at least to some extent on the desired treatment, andmay also depend on other considerations, such as tissue characteristics.

A basket catheter may be employed for ablation and other procedures(e.g., mapping) of the heart. The catheter system may include an outercatheter shaft also referred to as a “guiding introducer”. The guidingintroducer defines at least one lumen or longitudinal channel. Adelivery sheath is fitted through the guiding introducer. Topre-position the sheath at the appropriate location in the heart, adilator is first fitted through the sheath. In an example of a procedurewithin the left atrium, the sheath and the dilator are first inserted inthe femoral vein in the right leg. The sheath and dilator are thenmaneuvered up to the inferior vena cava and into the right atrium. Inwhat is typically referred to as a transseptal approach, the dilator ispressed through the interatrial septum between the right and left atria.A dilator needle may be used here to make an opening for the dilator topass through. The dilator expands the opening sufficiently so that thesheath may then be pressed through the opening to gain access to theleft atrium and the pulmonary veins. With the sheath in position, thedilator is removed and the basket catheter, needle, or other device(depending on the procedure) is fed into the lumen of the sheath andpushed along the sheath into the left atrium. When positioned in theleft atrium, various mapping and/or ablation procedures, such as theablation procedures described above, may be performed within the heart.

Several difficulties may be encountered, however, during theseprocedures using some existing basket catheters. For example, when thebasket catheter is expanded within the heart for a procedure, and thencollapsed again (e.g., to move to another location within the heart), aslowing or stoppage of the flow blood may occur between the splines ofthe basket catheter, especially at or near the apexes where the splinesare attached to the catheter. This slowing or stoppage of the flow ofblood may result in blood clot formation and may possibly lead to athrombus. A thrombus may decrease blood flow or even completely cut offblood flow, resulting in heart attack or stroke. Indeed, the risk ofthrombus formation continues to exist even after the basket catheter hasbeen removed following the procedure.

Thus, there remains a need for preventing thrombus while enablingmovement of the catheter shaft during a procedure.

BRIEF SUMMARY OF THE INVENTION

It is desirable to be able to deliver an anticoagulant (e.g.,heparinized saline) or other fluid between the splines of a basketcatheter during various procedures on the heart in order to reduce therisk of thrombus formation. It is further desirable to be able tomaintain a hemostatic seal at a distal end of the catheter fordelivering the anticoagulant or other fluid without fluid ingress intothe catheter shaft so that the fluid can be better directed between thesplines of the basket catheter. It is still further desirable to be ableto do all of this while retaining the ability to axially move adeployment mechanism, e.g., for a basket catheter.

These and other objectives can be accomplished by the catheter systemsand methods disclosed herein for conveying an anticoagulant or otherfluid between the splines of a basket catheter, especially at or nearthe apexes where the splines are attached to the catheter. A seal foruse with the catheters is configured to reduce or altogether preventfluid ingress into the patient's body while still retaining the abilityto axially move a deployment mechanism of the catheter, e.g., for thebasket catheter.

An exemplary basket catheter includes an outer tubing housing an innerfluid delivery tubing having at least one fluid delivery port. Aplurality of splines each connected at a proximal end of the splines tothe outer tubing and at a distal end of the splines to the inner fluiddelivery tubing. The inner fluid delivery tubing is operable to be movedin a first direction relative to the outer tubing to expand the splinesto a deployed position. The inner fluid delivery tubing is also operableto be moved in a second direction relative to the outer tubing tocollapse the splines to an undeployed position. A porous membrane isprovided over at least a portion of the inner fluid delivery tubinghaving the at least one fluid delivery port. A seal is provided at aproximal end of the porous membrane between the porous membrane and theouter tubing and between the porous membrane and the inner fluiddelivery tubing, the seal configured for irrigating between the splinesof the basket catheter while preventing fluid ingress into the cathetershaft.

An exemplary catheter system includes a guiding introducer housing adelivery sheath, and a basket catheter insertable through the guidingintroducer. The basket catheter includes an outer tubing housing aninner fluid delivery tubing, and a plurality of splines operable to bemoved to a deployed position and an undeployed position. A porousmembrane is provided within the outer tubing of the basket catheter overa fluid delivery port formed in a portion of the inner fluid deliverytubing of the basket catheter. A seal is molded to the porous membrane,the seal configured for irrigating between the splines of the basketcatheter, while permitting movement of the fluid delivery tube to movethe splines and preventing fluid ingress into the catheter shaft.

Another exemplary catheter system for delivering an anticoagulant orother fluid includes an outer shaft housing a delivery sheath, and abasket catheter insertable through the outer shaft. The basket catheterincludes an outer tubing housing an inner fluid delivery tubing, and aplurality of splines each connected at a proximal end of the splines tothe outer tubing and at a distal end of the splines to the inner fluiddelivery tubing. The inner fluid delivery tubing is operable to be movedin a first direction relative to the outer tubing to expand the splinesto a deployed position. The inner fluid delivery tubing is also operableto be moved in a second direction relative to the outer tubing tocollapse the splines to an undeployed position. A porous membrane sealedbetween the outer tubing & the basket catheter and the inner fluiddelivery tubing of the basket catheter. The porous membrane configuredfor irrigating between the splines of the basket catheter with theanticoagulant, while permitting movement of the fluid delivery tube tomove the splines.

The foregoing and other aspects, features, details, utilities, andadvantages of the present invention will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary embodiment of a cathetersystem. FIG. 1 a is a perspective view of an exemplary embodiment of abasket catheter which may be implemented with the catheter system inFIG. 1.

FIG. 2 is a perspective view of a tip portion of a sheath showing anexemplary embodiment of a basket catheter, wherein the splines of thebasket catheter are in a collapsed position. FIG. 2 a is across-sectional view of the tip portion of the sheath in FIG. 2 showingthe basket catheter with the splines in the collapsed position.

FIG. 3 is a perspective view of a tip portion of a sheath showing anexemplary embodiment of a basket catheter, wherein the splines of thebasket catheter are in an expanded position. FIG. 3 a is across-sectional view of the tip portion of the sheath in FIG. 2 showingthe basket catheter with the splines in the expanded position.

FIG. 4 a is a cross-sectional view taken along lines 2-2 in FIG. 2showing an exemplary support structure which may be implemented toprovide mechanical support for the inner fluid delivery tubing withinthe membrane. FIG. 4 b is a cross-sectional view of an alternativeexemplary embodiment of a support structure which may be implemented toprovide mechanical support for the inner fluid delivery tubing withinthe membrane.

DETAILED DESCRIPTION OF THE INVENTION

Several embodiments of a catheter system according to the presentinvention are depicted in the figures as the catheter system may be usedfor delivery of an anticoagulant (e.g., heparinized saline) or otherfluid between the splines of a basket catheter, especially at or nearthe apexes where the splines are attached to the catheter, in order toreduce the risk of thrombus formation during a medical procedure. Asdescribed further below, the catheter of the present invention providesa number of advantages, including, for example, facilitating delivery ofthe anticoagulant or other fluid to reduce thrombus formation withoutingress of fluid into the catheter shaft. These advantages are realizedwithout interfering with an actuating mechanism for a basket catheter.

Before continuing, it is noted that other components typical of systemswhich are conventionally implemented for such procedures, are not shownor described herein for purposes of brevity. Such components maynevertheless also be provided as part of, or for use with, the catheter.For example, catheter systems commonly include or are used inconjunction with an ECG recording system, and/or various input andoutput devices. Such components are well understood in the medicaldevices arts and therefore further explanation is not necessary for acomplete understanding of the invention.

FIG. 1 is a perspective view of an exemplary embodiment of a cathetersystem 10 which may implement fluid delivery means for conveying ananticoagulant or other fluid between splines of a basket catheter 25,especially at or near the apexes 31 a, 31 b where the splines areattached to the catheter. FIG. 1 a is a perspective view of an exemplaryembodiment of a basket catheter 25 which may be implemented with thecatheter system 10 in FIG. 1. The catheter system 10 may include ahandle 12 and connector 14 at the base or proximal end 15. An outercatheter shaft also referred to as a “guiding introducer” 16 having atubular body is connected to the connector 14 on the proximal end (e.g.,illustrated by reference number 15 in FIG. 1) of the catheter system 10.As used herein and commonly used in the art, the term “proximal” is usedgenerally to refer to components or portions of the catheter system 10,such as the handle 12 and connector 14 that are located or generallyorientated away from or opposite the heart or other target tissue whenthe catheter system 10 is in use. On the other hand, the term “distal”(e.g., illustrated in FIG. 1 by reference number 17) is used generallyto refer to components located or generally orientated toward the heartor other target tissue when the catheter system 10 is in use.

The guiding introducer 16 defines at least one lumen or longitudinalchannel. A delivery sheath 18 is fitted through the guiding introducer16. In one implementation, the guiding introducer 16 and sheath 18 arefabricated from a flexible resilient material, and are preferablyfabricated of materials suitable for use in humans, such asnonconductive polymers. Suitable polymers include those well known inthe art, such as polyurethanes, polyether-block amides, polyolefins,nylons, polytetrafluoroethylene, polyvinylidene fluoride, andfluorinated ethylene propylene polymers, and other conventionalmaterials. Some portions of the guiding introducer 16 and/or sheath 18may be braided for enhanced stiffness and torqueability.

In exemplary implementations, the guiding introducer 16 and sheath 18are each about two to four feet long, so that they may extend from theleft atrium through the body and out of the femoral vein in the rightleg and be connected with various catheter devices such as the connector14, one or more fluid control valves 1-3, and the like.

The sheath 18 is configured to receive and guide a device for carryingout the procedure (e.g., the basket catheter 25 shown in FIG. 1 a, FIGS.2-2 a, and 3-3 a) within the lumen to the target tissue. The sheath 18is pre-positioned in the appropriate location in the heart prior tointroduce a device. To pre-position the sheath 18 at the appropriatelocation in the heart, a dilator 20 is first fitted through the sheath18. In an example of a procedure within the left atrium, the sheath 18and the dilator 20 are first inserted in the femoral vein in the rightleg. The sheath 18 and dilator 20 are then maneuvered up to the inferiorvena cava and into the right atrium. In what is typically referred to asa transseptal approach, the dilator 20 is pressed through theinteratrial septum between the right and left atria. A needle may beused here to make an opening for the dilator 20 to pass through. Thedilator expands the opening sufficiently so that the sheath 18 may thenbe pressed through the opening to gain access to the left atrium and thepulmonary veins. With the sheath 18 in position, the dilator 20 isremoved and the basket catheter 25 (FIG. 1 a) may be fed into the lumenof the sheath 18 and pushed along the sheath 18 into the left atrium.When positioned in the left atrium, various procedures (e.g., ablationand mapping procedures) may be performed within the heart tissue usingthe basket catheter.

Once the sheath 18 is pre-positioned in the appropriate location in theheart, the basket catheter 25 may be at least partially extended outfrom the lumen at the distal end 17 of the sheath 18 (e.g., in thedirection illustrated by arrow 22 a) so that the basket catheter 25 maybe positioned adjacent the target tissue, and then expanded for themedical diagnostic procedure. The basket catheter 25 may also becollapsed and then retracted (e.g., in the direction of arrow 22 b)before removing the catheter system 10 from the body.

Before continuing, it is noted that the catheter system 10 has beendescribed as it may be inserted for procedures in the left atrium in thevicinity of or within the pulmonary veins of the heart. The cathetersystem 10, however, is not limited to such procedures, and may be usedfor procedures involving other target tissue in other areas of the heartand body.

The following discussion will now be with reference to the basketcatheter 25 shown in FIG. 1 a, and more particularly with reference tothe details shown in FIGS. 2 and 2 a and FIGS. 3 and 3 a. In thesefigures, an exemplary basket catheter 25 is shown as it may include anouter tubing 30 housing an inner fluid delivery tubing 32 having atleast one fluid delivery port 34 a-d near the apexes 31 a,b (shown inFIGS. 2 a and 3 a). The basket catheter 25 may also include a pluralityof splines 36 a-d (although only two of the splines 36 a, 36 b arevisible in FIGS. 2 and 2 a, and in FIGS. 3 and 3 a). The portion oneither end of the basket catheter 25 where the splines 36 a-d areattached to the catheter are referred to herein as the apexes 31 a, b.Fluid deliver ports 34 a-d may be positioned at or near the apexes. Itis noted that although fluid delivery ports 34 a-d and splines 36 a-dare shown in the drawings, the basket catheter 25 is not limited to anyparticular configuration (including number of splines or number orplacement of ports), as will be readily understood by those havingordinary skill in the art after becoming familiar with the teachingsherein.

Each spline 36 a-d is connected at the proximal end of the splines 36a-d to the sheath 18. In addition, each spline 36 a-d is connected atthe opposite or distal end of the splines 36 a-d to the inner fluiddelivery tubing 32. The inner fluid delivery tubing 32 is thus operableto be moved in a first direction (e.g., in the direction of arrow 38 ain FIG. 2 a) relative to the sheath 18 to expand the splines 36 a-d to adeployed position, as shown in FIGS. 3 and 3 a. The inner fluid deliverytubing 32 is also operable to be moved in a second direction (e.g., inthe direction of arrow 38 b in FIG. 3 a) relative to the sheath 18 tocollapse the splines 36 a-d to an undeployed position, as shown in FIGS.2 and 2 a. For example, the splines 36 a-d may be moved to theundeployed position following the procedure so that the basket catheter25 may be withdrawn through the delivery sheath 18 and guidingintroducer 16 of the catheter 10.

A basket deployment system may be implemented to control deployment ofthe splines 36 a-d. The basket deployment system may be connected to anyof a wide variety of catheter systems (e.g., to port 5 on the handle 12of catheter system 10 shown in FIG. 1). The basket deployment systemincludes a handle portion operatively associated with the inner fluiddelivery tubing 32 in such a manner that movement of the handle isdirectly translated into movement of the inner fluid delivery tubing 32.During operation, the inner fluid delivery tubing 32 moves in thedirection of arrow 38 a in FIG. 3 a when the handle is retracted orotherwise pulled back, thereby deploying the splines 36 a-d. Likewise,the inner fluid delivery tubing 32 moves in the direction of arrow 38 bwhen the handle is returned toward its starting position, therebycollapsing the splines 36 a-d.

In an exemplary embodiment, the handle may be spring-loaded (not shown).The spring acts to bias the handle in a fully extended or pulled backposition. A force must be applied to the handle in order to release thehandle, and hence return the inner fluid delivery tubing 32 toward itsstarting position. This may help ensure that the user does not leave thesplines 36 a-d of the basket in an expanded position when attemptingremoval of the catheter system from the patient's body. This may alsohelp ensure that the basket is not accidentally deployed duringplacement of the catheter system in the patient's body (doing so couldcause unintended damage to tissue or other parts of the patient's body).

Other embodiments of deployment systems are also contemplated and arenot limited to the specific implementation described above. For example,different mechanisms for controlling the distance the inner fluiddelivery tubing 32 can travel may be implemented.

The basket catheter 25 may also include a membrane 40 provided over atleast a portion of the inner fluid delivery tubing having the at leastone fluid delivery port. In an exemplary embodiment, the porous membrane40 is manufactured of a braided material such as, commercially availablebraided polyimide tubing. A porous membrane permits fluid egressdelivered through fluid delivery ports 34 a-d from in between the innerfluid delivery tubing 32 and the porous membrane. However, the membrane40 is not limited to use with porous materials.

A seal 42 is provided at a proximal end of the membrane 40. For example,the seal 42 may be molded to the membrane 40. The seal 42 may bejuxtapositioned on one side between the membrane 40 and the outer tubing30, and on the other side between the membrane 40 and the inner fluiddelivery tubing 32. The seal 40 may have an inner diameter which issmaller than the outer diameter of the inner fluid delivery tubing. Inaddition, the seal 40 may have an outer diameter larger than the innerdiameter of the outer tubing. The specific diameters may vary dependingon a number of design considerations, such as, the diameter of the outersheath 18 or other components of the catheter 10. Sizing the diametersin such a manner enables the seal 40 to provide a snug fit between therespective tubing 30 and 32, and the membrane 40. Accordingly, fluidtraveling through fluid delivery tube 32 (e.g., in the direction ofarrows 45) is forced out through the distal end of the membrane 40(e.g., as illustrated in FIGS. 3 and 3 a by discharged fluid 45) forirrigating between the splines 36 a-d of the basket catheter 25. Theseal prevents fluid ingress back within the catheter shaft so that theapexes are effectively irrigated.

The seal 40 may be manufactured of any suitable material. In anexemplary embodiment, the seal 40 may be manufactured of a low durometermaterial, such as rubber, although plastic, metal or other material mayalso be used. When a low durometer material is put under pressure thematerial has a “memory” (tending back toward its original shape),enabling a seal under little or even no pressure. In any event, the seal40 may be made of a material that enables the seal 40 to prevent fluidingress outside of the heart wall while still permitting movement of thefluid delivery tube 32 in the first and second directions 38 a and 38 b,respectively, so that the splines can still be expanded and collapsed.

In an exemplary embodiment, at least one axial support may be providedbetween the inner fluid delivery tubing 32 and the membrane 40. Theaxial support is configured for fluid flow between the inner fluiddelivery tubing and the porous membrane. The axial support is alsoconfigured to provide mechanical support for maintaining the inner fluiddelivery tubing 32 substantially centered within the membrane 40.

Exemplary configurations of axial support structure 50 are shown in FIG.4 a-b. FIG. 4 a is a cross-sectional view taken along lines 2-2 in FIG.2. In FIG. 4 a, the support structure 50 includes a plurality of ridges52 provided between the inner fluid delivery tubing 32 and the membrane40. In this embodiment, the support structure 50 is substantiallystar-shaped to maintain the inner fluid delivery tubing 32 approximatelyin the center of the membrane 40.

FIG. 4 b is a cross-sectional view of an alternative exemplaryembodiment of an axial support structure 50′ which may be implementedbetween the inner fluid delivery tubing 32 and the membrane 40. In thisembodiment, the support structure 50′ is substantially radial-shaped.This embodiment also maintains the inner fluid delivery tubing 32approximately in the center of the membrane 40.

The support structure 50 or 50′ may include one or more interstitialspaces (e.g., spaces 54 or 54′ formed by the support structure as shownin FIG. 4 a-b). These interstitial spaces enable the fluid dispensedthrough ports 34 a-d of the inner fluid delivery tubing through thespace defined between the inner fluid delivery tubing 32 and themembrane 40 and to be discharged, e.g., as shown in FIGS. 3 and 3 a.

It should be noted that although the cross-section shown in FIG. 4 a-bis depicted as a circular cross-section, it is noted that thecross-section may intentionally or unintentionally have a wide varietyof cross-sectional configurations and areas, and need not be circular.For example, manufacturing irregularities may result in differentcross-sectional configurations. Or for example, differentcross-sectional configurations may be intentionally selected to achievedesired properties.

Of course other designs of the support structure may also be implementedas will be readily understood by those having ordinary skill in the artafter becoming familiar with the teachings herein. It is noted that thesupport structure need not maintain the inner fluid delivery tubing inthe center of the membrane 40. It is only desired that the inner fluiddelivery tubing be maintained in a substantially constant positionwithin the diameter of the membrane 40 for uninterrupted flow of thefluid during the procedure.

The particular types and configuration of support structure used willdepend at least to some extent on design considerations. Exemplarydesign considerations may include, but are not limited to, the materialand desired structural properties, the length, shape, andcross-sectional area of the sheath. And of course, the design parametersmay be different for various procedures or physician preferences.

It is noted that the various embodiments of catheter system 10 describedabove with reference to the figures may also be implemented with a widevariety of different sensors. In an exemplary embodiment, the cathetersystem 10 may include one or more piezoelectric sensor embedded in thesheath 18 or the splines 36 a-d. The piezoelectric sensor generateselectric signals in response to stresses caused by contact with thetissue. Radiopaque sensors may also be used. Still other exemplarysensing devices may include pressure, thermistor, thermocouple, orultrasound sensors. In addition, more than one sensor or type of sensormay be implemented to provide additional feedback to the user. In anyevent, when the sheath 18 or the splines 36 a-d are positioned incontact with and/or moved over a tissue, the sensors may be implementedto generate an electrical signal corresponding to stress caused by thiscontact and/or movement for tissue contact assessment.

Electrical wiring (not shown) may also extend through the lumen of thecatheter system 10 to enable these sensors. The electrical wiring mayconvey electrical signals from the sensor(s) to a dataacquisition/processing/output device (also not shown), such as, e.g., anechocardiogram (ECG) device. Alternatively, a wireless connection may beimplemented, e.g., by providing a transmitter in the catheter and areceiver in association with the data acquisition/processing/outputdevice. Accordingly, the electrical signals from the sensor(s) may beviewed by the user, e.g., as output on an electrical monitoring device.The resulting electrical signal may be processed and/or otherwise outputfor the user so that the user is able to assess tissue contact by thecatheter system 10.

It is noted that any suitable analog and/or digital device may beimplemented for outputting the electrical signals generated by thesensor(s) to a user. In addition, the electrical signals may be furthercharacterized using a suitable processing device such as, but notlimited to, a desktop or laptop computer. Such processing device may beimplemented to receive the voltage signal generated by the contactassessment sensor(s) and convert it to a corresponding contact conditionand output for the user, e.g., at a display device, an audio signal, ortactile feedback or vibrations on the handle of the catheter. In anyevent, circuitry for conveying output of the piezoelectric sensor to auser in one form or another may be readily provided by those havingordinary skill in the electronics arts after becoming familiar with theteachings herein.

Although several embodiments of this invention have been described abovewith a certain degree of particularity, those skilled in the art couldmake numerous alterations to the disclosed embodiments without departingfrom the spirit or scope of this invention. References are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations as to the position,orientation, or use of the invention. In addition, various combinationsof the embodiments shown are also contemplated even if not particularlydescribed. Changes in detail or structure, such as but not limited tocombinations of various aspects of the disclosed embodiments, may bemade without departing from the spirit of the invention as defined inthe appended claims.

1. A basket catheter for conveying an anticoagulant or other fluid forirrigation, comprising: an outer tubing housing an inner fluid deliverytubing having at least one fluid delivery port; a plurality of splineseach connected at a proximal end of the splines to the outer tubing andat a distal end of the splines to the inner fluid delivery tubing, theinner fluid delivery tubing operable to be moved in a first directionrelative to the outer tubing to expand the splines to a deployedposition, and the inner fluid delivery tubing operable to be moved in asecond direction relative to the outer tubing to collapse the splines toan undeployed position; a membrane provided over at least a portion ofthe inner fluid delivery tubing having the at least one fluid deliveryport; and a seal provided at a proximal end of the membrane between theouter tubing and the inner fluid delivery tubing, the seal configuredfor irrigating between the plurality of splines of the basket catheterwhile preventing fluid ingress back into the outer tubing of the basketcatheter.
 2. The basket catheter of claim 1, wherein the seal iscomprised of a low durometer material.
 3. The basket catheter of claim1, wherein the seal is molded to the membrane, the seal permittingmovement of the fluid delivery tube to move the splines.
 4. The basketcatheter of claim 1, wherein the seal has an inner diameter smaller thanthe outer diameter of the inner fluid delivery tubing.
 5. The basketcatheter of claim 1, wherein the seal has an outer diameter larger thanthe inner diameter of the outer tubing.
 6. The basket catheter of claim1, wherein the seal prevents fluid ingress inside the catheter wallwhile permitting movement of the fluid delivery tube in the first andsecond directions to expand and collapse the splines.
 7. The basketcatheter of claim 1, further comprising at least one axial supportbetween the inner fluid delivery tubing and the membrane.
 8. The basketcatheter of claim 7, wherein the at least one axial support isconfigured to maintain the inner fluid delivery tubing substantiallycentered within the membrane.
 9. The basket catheter of claim 7, whereinthe at least one axial support is configured for fluid flow between theinner fluid delivery tubing and the membrane.
 10. The basket catheter ofclaim 7, wherein the at least one axial support includes a plurality ofridges formed on the inner fluid delivery tubing.
 11. The basketcatheter of claim 1, wherein the membrane is porous.
 12. The basketcatheter of claim 1, wherein the membrane is comprised at least in partof a braided material.
 13. The basket catheter of claim 1, wherein theporous membrane is comprised at least in part of braided polyimidetubing.
 14. A catheter system comprising: a guiding introducer housing adelivery sheath; a basket catheter insertable through the guidingintroducer, the basket catheter including an outer tubing housing aninner fluid delivery tubing, and a plurality of splines operable to bemoved to a deployed position and an undeployed position; a membraneprovided within the outer tubing of the basket catheter over a fluiddelivery port formed in a portion of the inner fluid delivery tubing ofthe basket catheter; and a seal molded to the membrane and sealingbetween the outer tubing housing and the inner fluid delivery tubing,for irrigating between the plurality of splines of the basket catheter,while permitting movement of the fluid delivery tube to move the splinesand preventing fluid ejected near the plurality of splines fromingressing back into the outer tubing.
 15. The catheter system of claim14, wherein the seal is comprised of a low durometer material.
 16. Thecatheter system of claim 14, wherein the seal has an inner diametersmaller than the outer diameter of the inner fluid delivery tubing, andthe seal has an outer diameter larger than the inner diameter of theouter tubing.
 17. The catheter system of claim 14, further comprisingaxial support between the inner fluid delivery tubing and the membrane.18. The catheter system of claim 17, wherein the axial support isconfigured in a star pattern to maintain the inner fluid delivery tubingsubstantially centered within the membrane.
 19. The catheter system ofclaim 14, wherein the membrane is porous and comprised at least in partof braided polyimide tubing.
 20. A catheter system for delivering ananticoagulant or other fluid comprising: an outer shaft housing adelivery sheath; a basket catheter insertable through the outer shaft,the basket catheter including: an outer tubing housing an inner fluiddelivery tubing, and a plurality of splines each connected at a proximalend of the splines to the outer tubing and at a distal end of thesplines to the inner fluid delivery tubing, the inner fluid deliverytubing operable to be moved in a first direction relative to the outertubing to expand the splines to a deployed position, and the inner fluiddelivery tubing operable to be moved in a second direction relative tothe outer tubing to collapse the splines to an undeployed position; aseal between the outer tubing of the basket catheter and the inner fluiddelivery tubing of the basket catheter, the seal preventing fluidingress back into the outer tubing of the basket catheter; and a porousmembrane sealed by the seal, the porous membrane configured forirrigating between the plurality of splines of the basket catheter withthe anticoagulant, while permitting movement of the fluid delivery tubeto move the splines.
 21. The catheter system of claim 20, wherein theporous membrane is sealed by a low durometer material.
 22. The cathetersystem of claim 20, further comprising axial support of the porousmembrane between the inner fluid delivery tubing and the porousmembrane.
 23. The catheter system of claim 20, wherein the porousmembrane is comprised at least in part of braided tubing.